High-pressure single-crystal X-ray structural analyses of isostructural MFM-133(M) (M = Zr, Hf) of flu topology and incorporating the tetracarboxylate ligand TCHB [HTCHB = 3,3',5,5'-tetrakis(4-carboxyphenyl)-2,2',4,4',6,6'-hexamethyl-1,1'-biphenyl] and {M(μ-OH)(OH)(COO)} clusters confirm negative linear compressibility (NLC) behavior along the c axis. This occurs via a three-dimensional wine-rack NLC mechanism leading to distortion of the octahedral cage toward a more elongated polyhedron under static compression. Despite the isomorphous nature of these two structures, MFM-133(Hf) shows a higher degree of NLC than the Zr(IV) analogue. Thus, for the first time, we demonstrate here that the NLC property can be effectively tuned in a framework material by simply varying the inorganic component of the frameworks without changing the network topology and structure.

High pressure crystallographic studies on [1,4-C6H4{PPh2(AuCl)}2] (1) reveal the largest pressure-induced contraction of an aurophilic interaction observed for any Au(i) complex; Hirshfeld surface analysis and Raman spectroscopy reveal the presence of several types of intermolecular interaction, which play an important role in the behaviour of 1 as a function of pressure.

Recrystallization of [PdCl2([9]aneS2O)] ([9]aneS2O = 1-oxa-4,7-dithiacyclononane), 1, and [PtCl2([9]aneS2O)], 2, by diffusion of Et2O vapor into solutions of the complexes in MeNO2 yielded three phases of 1 and two phases of 2. The known phase of 1, herein designated α-1, was obtained under ambient conditions. A second phase, designated β-1, was initially also obtained by this method; however, following the advent of a third phase, γ-1, all subsequent efforts over a period of a year to crystallize β-1 yielded either γ-1, obtained by carrying out the recrystallization at elevated temperature, or α-1, commonly found throughout the study. This persistent absence of a phase which could initially be crystallized with ease led us to the conclusion that β-1 was an example of a “disappearing polymorph”. The first phase obtained of 2, designated α-2, was obtained by recrystallization under ambient conditions and is isomorphous and isostructural with α-1. The second phase β-2 was obtained by slight elevation of the recrystallization temperature and was found to be isomorphous and isostructural with β-1. Subsequently, β-2 was used to seed the growth of the disappearing polymorph β-1. No third phase of 2 (γ-2) has been isolated thus far.

Two independent mol­ecules of the title solvated complex, [V(C16H14N2O2)O]·CH3OH, also known as [N,N′-bis­(salicyl­idene)ethyl­enedi­amine]­oxidovanadium(IV) or vanadyl salen, crystallize in the asymmetric unit. Each disordered methanol solvent mol­ecule [occupancy ratios 0.678 (4):0.322 (4) and 0.750 (5):0.250 (5)] is linked to a [N,N′-bis­(salicyl­idene)ethyl­enedi­amine]­oxidovanadium(IV) mol­ecule by an O—H⋯O hydrogen bond and to others by C—H⋯O hydrogen bonds. The resulting extended structure consists of a bilayer of mol­ecules parallel to the ab plane. Despite the fact that solvates are common in complexes derived from substituted analogues of the N,N′-bis­(salicyl­idene)ethyl­enedi­amine ligand, the title solvate is the first one of [N,N′-bis­(salicyl­idene)ethyl­enedi­amine]­oxidovanadium(IV) to be structurally characterized. The two vanadyl species have very similar inter­nal geometries, which are best characterized as distorted square-based pyramidal with the vanadium atom displaced from the N2O2 basal plane by 0.5966 (9) Å in the direction of the doubly-bonded oxide ligand.

The presence of competing donor sites in L1–L4 influences their reactivity towards dihalogens and interhalogens.